1. Field of the Invention
The present invention relates to air circulation apparatus, and in particular to apparatus wherein cooler air is drawn upwardly from the lower portion of the room and discharged just below the ceiling so as to force the warmer air in the upper portion of the room downwardly.
2. Description of the Prior Art
The phenomenon whereby warm air in a room rises and colder air descends results in a temperature gradient that decreases heating efficiency and creates drafts which render the room uncomfortable. The reduction in heating efficiency results from the fact that the thermostat is normally located approximately halfway between the floor and ceiling and therefore senses an ambient temperature which is lower than the temperature of the air above the level of the thermostat. To maintain the temperature of the room at the desired level, therefore, the heating plant must raise the temperature of the air within the upper portion of the room at a level higher than that of the comfort setting. The occupants of the room rarely come into contact with this higher temperature air, however, and the energy required to heat it is therefore wasted.
Another undesirable effect of temperature stratification is the loss of heat through the ceiling, especially in the case of a second story rooms. It is a commonly recognized fact that the greatest heat loss during the winter months occurs through the ceiling of the top floor. In most cases, the walls of the attic are not insulated so that the attic temperature is very close to that of the outside ambient. Although there may be insulation in the floor of the attic, it is generally not thick enough to reduce the transmission of heat to an acceptably low level and the ceiling of the second floor therefore acts as a large heat sink. With the warmest air occupying the stratum next to the ceiling, the difference in temperature between the relatively cold attic and the relatively warm room is at a maximum. This condition, in turn causes maximum heat transfer between the interior room and the attic.
In order to avoid the problems discussed above, a number of prior art apparatuses have been proposed whereby air from the upper portion of the room is pumped to the lower portion of the room, or vice versa. One example of such an apparatus is disclosed in U.S. Pat. No. 3,827,342 and comprises a vertical tube having an opening on its upper end and being supported on a base, which includes a plurality of intake passageways. A motor driven blower, which is mounted within the upper portion of the tube, draws cold air from the area near the floor and discharges it through the top opening whereupon it is dispersed by a conical deflector. The deflector also serves as a stabilizer and is urged against the ceiling by means of a coil spring.
A further example of prior art air circulation devices of this general type is shown in U.S. Pat. No. 3,173,353. This patent disclosed a device which is free standing and comprises a plurality of telescoping sections supported on a base, and a motor driven blower within the base which draws ceiling air downwardly and out through a discharge opening in the base. A somewhat similar device is shown in U.S. Pat. No. 3,973,479 in which one fan draws air from the floor level and discharges it at the ceiling level via one flow path, and a second fan draws air in from the ceiling level and discharges it at the floor level via a separate flow path.